Magnet coil having cooling means



5 Sheets-Sheet 1 mlm@ Nw ww GN NN .ON RN R N \WN QN EQ lll I Il!! I'lill Il I l P. L. KUSTOM ET AL MAGNET COIL HAVING COOLING MEANS Dec. 27, 1966 Filed Sept. 1l, 1964 NN o O o Q omm O WINNIE- l f NHG,N\i I T w I -I-||:|||l|-| O w @i O l /mw\\ ww f\l\L Dec. 27, 1966 R. L. KUSTOM ET AL MAGNET COIL HAVING COOLING MEANS 5 Sheets-Sheet 2 Filed sept. 11, 1964 ,45 .29, if?, M

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Dec. 27, 1966 R. L. KUSTOM ETAL MAGNET COIL HAVING COOLING MEANS 5 Sheets-Sheet 5 Filed sept. 11, 1964 United States Patent Oce 3,295,082 Patented Dec. 27, 1965 Filed seni. 11, 1964, ser. No. 395,96s s claims. (ci. 335-299) The invention described herein was made in the course of, or under, a contract with the U.S. Atomic Energy Commission.

This invention relates to a magnet coil. More particularly, the invention relates to a conductor construction for a magnet coil with good cooling and current capacity.

Recently spark chambers have been used in a magnetic iield as part of high-energy-physics experiments for the observance of particle decays and interactions. Magnets used for this purpose have large air gaps for the installation of spark chambers. Since in these experiments particle moments may vary rather widely, the magnet operates over a wide range of eld and power levels. The magnet cannot operate over such a wide range if it is made with conventional hollow copper conductors. To achieve a wider range of operation, we have designed a novel magnet in which copper tapes or strips are used along with spacing elements to accommodate coolant tlowing over the copper strips.

In the drawings:

FIG. 1 is fragmentary elevation, with parts broken away, of copper strips and associated insulating and spacing elements;

FIG. 2 is a sectional View taken on the line 2 2 of FIG. 1;

FIG. 3 is a plan view, with parts broken away, of the magnet of the present invention;

FIG. 4 is a sectional View taken on line 4 4 of FIG. 3; and

FIG. 5 is a sectional view taken on line 5-5 of FIG. 3.

As shown in FIGS. 1 and 2, two long facing copper strips 20 and 21 of equal width and thickness are kept spaced from one another by a plurality of spaced insulating cross pieces 22. which are located between the strips 20 and 21 and extend across them and beyond their side edges. The ends of the cross pieces 22 are joined by copper rivets 23 to two longitudinal insulating members 24, which extend along the side edges of the copper strip 21 in the same plane as the strip and have the same thickness as the strip. A pair of longitudinal insulating members 25 extend along the side edges of the copper strip 20 in the same plane as the strip and have the same thickness as the strip. The cross pieces 22 are spaced from one another longitudinally of the copper strips 2d and 21 and cooperate with the strips and the longitudinal members 24 and 25 to form transverse coolant channels 26 for the copper strips. Alongside the copper strip 21 lies insulating sheet means 27, which is actually two sheets one on top of the other. The sheet means 27 has the same width as the over-all width of the copper strip 21 and longitudinal members 24 and that of copper strip 20 and long1- tudinal members 2.5.

The various parts just described are brought together by being unwound from various reels (not shown) and wound as a group about an inner annular wall 28 of an annular housing 29 to form a coil 30 shown in FIG. 3. The wall 28 and the housing 29 are rectangular with rounded corners. The coiling of the parts takes place about an axis 31 coincident with the center of the rectangle of the inner wall 28 and perpendicular to the plane of the rectangle. The axis 31 appears as a point in FIG. 3 because of being perpendicular to the plane of the paper. The bending of the copper strips 20 and 21, longitudinal members 24 and 25, and sheet means 27 takes place perpendicularly to the lengths thereof. Each turn of the coll includes all of the parts described and shown in FIGS. l and 2. The insulating sheet means 27 -of one turn of the coil lies against the copper strip 20 and longitudinal members 25 of the next turn.

The inner wall 28 may be formed of aluminum and, as shown in FIG. 5, has some insulating layers 32 between its outer surface and the coil. The housing 29 has an exterior annular wall 33 of aluminum which is generally rectangular in shape and surrounds the coil 30. Insulatmg layers 34 lie between the coil 30 and the outer Wall 33. The housing 29 has end members 35 of annular shape, which are bolted to annular flanges 36 welded to the walls 28 and 33. The end members 35 are of aluminum and have insulating coverings 37 on their inner sides facing the coil 30.

Between the ends of the coil 30 and the end members 35 lie non-conducting baies 38 and 39. Bacies 38 and baies 39 are, respectively, at the upper end and at the lower end of the coil 30 as viewed in FIGS. 4 and 5 and so are termed upper baiiies and lower battles, respectively. As shown in FIGS. 3 and 4, the upper bafiies 38 are distributed about the upper end of the coil 30 in space-d relation to one another and extend across the turns of the coil. Two of the baies 38 extend across two opposed curved corners of the coil 30, and an inlet 4th and an outlet 41 for liquid coolant are provided at the two remaining corners of the housing 29 and are connected to the upper end member 35. The lower battles 39 are distributed about the lower end of the coil 30 and extend across the turns of the coil. There are no baffles 39 at the corners of the coil 30. Except at the corners of the coil where the inlet 40 and outlet 41 are located, the baies 38 and 39 alternate with one another as viewed on FIG. 3 or when projected on a plane perpendicular to the axis 31 of the coil 30. The upper baffles 38 and the lower bailles 39 cooperate with their respective end members 35 and the respective ends of the coil 30 to form upper and lower headers 42 and 43, respectively. The upper headers 42 overlap the lower headers 43 in staggered relation. Except at the corners of the coil 30 where the inlet 40 and outlet 41 are located, each header 42 or 43 overlaps just one of the headers 43 or 42. Because there are no bal-lies at the corners where the inlet 40 and outlet 41 are located, each of the lower headers 43 at the inlet and the outlet overlap three upper headers 42, namely, the one at the corner and two adjacent ones.

Because of this arrangement at the corners just described the liquid coolant, which is preferably water with the minerals removed, upon entering the magnet at the inlet 40, splits into two branches, which are reunited at the corner where the outlet 41 is located for departure from the magnet. The one branch of coolant proceeds by the lower and right-hand sides of the magnet, and the other, by the left-hand and upper sides, all as viewed in FIG. 3. Because of the partially overlapping staggered relation of the upper and lower headers 42 and 43 except at the corners where the inlet 40 and `outlet 41 are located, the branches of coolant flow back and forth between the upper headers 42 and lower headers 43 through the coolant channels 26 between the copper strips 20 and 21.

As seen in FIG. 4, coolant enters through the inlet 40 into the upper header 42 directly adjacent thereto and flows across the coil 30 through the channels 26 to the lower header 43 at the corner. One branch of the coolant moves to the right as viewed in FIG. 4 and then upward through the coolant channels of the coil 30 to upper header 42 directly adjacent the upper header 42 at the inlet 4t). The other branch of the coolant ows in the lower header 43 in the corner into the plane of the paper as seen in FIG. 4 and then upwardly across the coil through coolant channels 26 to the upper header behind the upper header 42 at the inlet 40 as viewed in FlG. 4.

Each pass or" coolant across the coil 30 between an upper header 42 and a lower header 43 occurs in a multiplicity of paths through the associated coolant channels, because each header extends over the entire radial dimension of the coil 30 which has many turns, and because on each turn there is a number of coolant channels 26 in the length of a turn of the coil 30 between an upper baille 3S and the next lower baie 39.

The two copper strips and 21 are electrically connected to one another at both ends so as to constitute, in effect, a single conductor. This is accomplished, as shown in FIG. 1, by means of a thin copper blade 44 brazed between adjacent ends of the strips 20 and 21, to which blade current is supplied to energize the magnet. A similar blade (not shown) is brazed vbetween the other ends of the strips 2t) and 21.

There is little, if any, current leakage between turns of the coil through the water in the headers 42 and 43. This is due to the use of demineralized water as the coolant and to the relatively long current path through the water around the longitudinal insulating members 24 and 25 arranged at the side edges of the copper strips 21 and 20. Thus, the shortest current path between adjacent turns of the coil 30 is equal to twice the width of the strip 24 or 25 plus twice the thickness of the strip 24 or 25 plus the thickness of the insulating sheet means 27.

The copper strips 20 and 21 may be .0323 thick and 8" wide. The cross pieces 22 may be 8%" long M2" wide, and .030" thick and have a spacing of 1A". The longitudinal pieces 24 and 25 may be 2/s wide and .030" thick. The cross pieces 22 and longitudinal pieces 24 and 25 may be of polypropylene. The insulating sheet means 27 may be of two polypropylene sheets each .003 thick and 8% wide. Tw-o sheets are used for the sheet means 27 so that there is little chance of a short between turns of the coil at holes in the sheets because the holes are unlikely to register with one another. The coil 30 may be 12%" in radial thickness and have about 120 turns. Two opposite legs of the coil 30 may have a spacing of about 63 from inside t-o inside. The two remaining legs of the coil may have a spacing of about 53 from inside to inside.

The use of two spaced copper strips 20 and 21 to form a single conductor with a plurality of coolant channels 26 extending thereacross assures high current capacity and very adequate cooling. At the same time the two copper strips and the closely spaced cross strips 22 provide an adequately stiff construction to resist relative movement of the strips 20 and 21 due to operation of the magnet and keep the channels 26 large enough in area for adequate flow of coolant therethrough.

In a spark chamber for a mass spectrometer, two aligned and axially spaced magnet coils 30 may be mounted in a steel framework 7' x 8 x 10.

It is understood that the invention is not to be limited by the details given herein but that it may be modified within the scope of the appended claims.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A magnet comprising an annular coil comprising two copper strips electrically connected to one another at their ends, a plurality of insulating cross pieces located between the copper strips in contact therewith and extending across them and beyond their side edges, the insulating pieces being spaced from one another longitudinally of the copper strips and distributed over their length, a first pair of longitudinal insulating members extending along the side edges of one copper strip in overlapping relation to the ends of the cross pieces, and a second pair of insulating members extending along the side edges of the other copper strip in overlapping relation to the ends of the cross pieces, the cross pieces and longitudinal members cooperating with the copper strips to form transverse cooling passages over the length of the copper strips, and insulating sheet means extending along one copper strip and the associated longitudinal members.

2. A magnet comprising an annular coil comprising two copper strips electrically connected to one another at their ends, a plurality of insulating cross pieces located between the copper strips and extending across them and beyond their side edges, the insulating pieces being spaced from one another longitudinally of the copper stripsand distributed over their length, a iirst pair of longitudinal insulating members extending along the side edges of one copper strip in overlapping relation t0 the ends of the cross pieces, means attaching the longitudinal members to the ends of the cross pieces, a second pair of insulating members extending along the side edges of the other copper strip in overlapping relation to the ends of the cross pieces, the combined width of one copper strip and the associated longitudinal members being about equal to that of the other copper strip and the associated longitudinal members, the cross pieces and longitudinal members cooperating with the copper strips to form transverse cooling passages over the length of the copper strips, and insulating sheet means extending along one copper strip and the associated longitudinal members, the side edges of the sheet being even with the outer edges of both pairs of longitudinal members, the aforesaid elements being so wound as a unit in the said coil as to locate successive turns of the coil radially outward of one another and in contact with one another and the side edges of the turns generally in two parallel planes perpendicular to the axis of the coil.

3. A magnet comprising an annular coil comprising two copper strips of equal width electrically connected toone another at their ends, a plurality of insulating cross pieces located between the copper strips and extending across them and beyond their side edges, the insulating pieces being spaced from one another longitudinally of the copper strips and distributed over their length, a iirst pair of longitudinal insulating members extending along the side edges of one copper strip in overlapping relation to the ends of the cross pieces and having the same thickness as the said one copper strip, means attaching the longitudinal members to the ends of the cross pieces, a second pair of insulating members extending along the side edges of the other copper strip in overlapping relation to the ends of the cross pieces and having the same thickness as the said other copper strip, the combined width lof one copper strip and the associated longitudinal members being about equal to that of the other copper strip and the associated longitudinal members, the cross pieces and longitudinal members cooperating with the copper strips to form transverse cooling passages over the length of the copper strips, and insulating sheet means extending along one copper strip and the associated longitudinal members, the side edges of the sheet being even with the outer edges of both pairs of longitudinal members, the aforesaid elements being so wound as a unit in the said coil as to locate successive turns of the coil radially outward of one another and in contact with one another and the side edges of the turns generally in two parallel planes perpendicular to the axis of the coil.

4. The magnet specified in claim 3 and further com* prising a housing enclosing the annular winding and including two sets of internal baiiies, the baies of one set of one set engaging one end of the coil and being distrbuted over said one end in spaced relation to one another across the side edges of the turns so as to form in the housing one set of headers communicating at the said one end of the housing with the transverse channels rbetween the copper strips, the battles of the other set engaging the other end of the coil and being distributed over said other end in spaced relation to one another across the side edges of the turns so as to form in the housing another set of headers communicating at the said other end of the coil with the transverse passages between the copper strips, the headers of said one set being so related to those of said other set as to cause each header of said one set when projected on a plane perpendicular to the axis of the coil to overlap two headers of said other set when -projected on said plane, whereby coolant entering the housing at a header of one set flows in one direction through certain of the said transverse passages between the copper strips to a header of the other set, then in the opposite direction through others of said transverse passages to the next header of the said one set, then in the said one direction through stilll others of said transverse passages to the next header of the said other set, then in the said opposite direction through still others of said transverse passages to the second next header of the said one set, etc.

5. The magnet specified in claim 4, the housing being in the form of a ring and having a coolant inlet and a coolant outlet located opposite one another across the ring and comunicating directly with separate headers of the aforementioned sets of headers, the coolant, after entering one of said separate headers via the inlet and crossing the copper strips, splitting into two branches, one following one path back and forth across the copper strips about the ring toward the outlet, the other following another path in a different ldirection back and forth across the copper strips about the ring toward the outlet, the branches being united in the ring adjacent the outlet.

f 6. The magnet specilied in claim 4, the housing being in the shape of a ring and having a coolant inlet and a coolant outlet located opposite one another across the ring and communicating directly with a irst header and a second header, respectively, of said other set of headers, a certain header of said one set of headers when projected on a plane perpendicular to the core axis overlapping said first header and the two adjacent headers of said other set when projected on said lplane, a certain other header of said one set of headers when projected on said plane overlapping said second header and the two adjacent headers of said other set when projected on said plane, coolant entering the housing at said rst header via the inlet, crossing the copper strips through transverse channels therein to the said certain header, and then splitting into two branches going on opposite sides about the ring of the housing, one branch crossing the copper strips from the said certain header to the one of two headers of said other set previously described as adjacent `said iirst header, the other branch crossing the copper strips from the said tirst header to the other of two headers of said other set previously described as adjacent said rst header, the branches being united in the said other certain header for ow of the coolant from the said other certain header across the copper strips to said second header and out of the housing via the outlet, one branch reaching the said other certain header by flowing across the copper strips from one -of two headers of said other set previously described as adjacent said second header, the other branch reaching the said other certain header by flowing across the copper strips from the other of two headers of said other set previously described as adjacent said second header.

References Cited by the Examiner UNITED STATES PATENTS 2,863,130 12/1958 Gray et al 336-207 BERNARD A. GILHEANY, Primary Examiner. G. HARRIS, Assistant Examiner. 

1. A MAGNET COMPRISING AN ANNULAR COIL COMPRISING TWO COPPER STRIPS ELECTRICALLY CONNECTED TO ONE ANOTHER AT THEIRS ENDS, A PLURALITY OF INSULATING CROSS PIECES LOCATED BETWEEN THE COPPER STRIPS IN CONTACT THEREWITH AND EXTENDING ACROSS THEM AND BEYOND THEIR SIDE EDGES, THE INSULATING PIECES BEING SPACED FROM ONE ANOTHER LONGITUDINALLY OF THE COPPER STRIPS AND DISTRIBUTED OVER THEIR LENGTH, A FIRST PAIR OF LONGITUDINAL INSULATING MEMBERS EXTENDING ALONG THE SIDE EDGES OF ONE COPPER STRIP IN OVERLAPPING RELATION TO THE ENDS OF THE CROSS PIECES, AND A SECOND PARI OF INSULATING MEMBERS EXTENDING ALONG THE SIDE EDGES OF THE OTHER COPPER STRIP IN OVERLAPPING RELATION TO THE ENDS OF THE CROSS PIECES, THE CROSS PIECES AND LONGITUDINAL MEMBERS COOPERATING WITH THE COPPER STRIPS TO FORM TRANSVERSE COOLING PASSAGES OVER THE LENGTH OF THE COPPER STRIPS, AND INSULATING SHEET MEANS EXTENDING ALONG THE COPPER STRIP AND THE ASSOCIATED LONGITUDINAL MEMBERS. 